This invention relates to endodontic tools, and in particular, to tools used during and after an endodontic root canal preparation procedure, to more effectively clean the root canal system prior to obturation.
Following tooth maturation, the dental pulp is harbored within the structural elements of the tooth. Frequently, and for a variety of reasons, the pulp is irreversibly injured, resulting in inflammatory and infectious conditions which often adversely affect the tooth, its supporting structures, and the patient's health. Clinically, as an alternative to extraction, root canal treatment is performed and ideally directed towards the elimination of pulp, bacteria, and related irritants from the root canal system, followed by three-dimensionally filling the root canal space with an inert, biocompatible, dimensionally stable, filling material, such as gutta percha. Ideally, the obturation procedures will fill not just the main canal, but the fins, webs, cul-de-sacs, lateral canals, and all portals of exit between the root canal system and the tooth's attachment apparatus.
Root canal procedures are common. Central to a successful endodontic treatment has been the use of chemical reagents during mechanical root canal shaping procedures to completely clean all aspects of the root canal system. The chemicals used to enhance canal debridement and disinfection during cleaning and shaping procedures potentially reach all aspects of the root canal system. The most popular chemicals currently used during canal preparation to actively assist in cleaning and disinfecting include bleach, hydrogen peroxide, and chelating agents. Often, a 2%-5% solution of a clear, pale, greenish-yellow strongly alkaline solution of sodium hypochlorite (NaOCl) and ethylenediaminetetracetic acid (EDTA) are used.
During canal preparation, a solution of NaOCl is liberally irrigated into the root canal space where its solvent action facilitates the digestion and removal of pulp, bacteria, viruses, spores, endotoxins and other irritants generated by the microorganisms. This solution has the potential to circulate, penetrate and, hence, clean into all aspects of the root canal space. However, studies have shown that even the most thorough use of sodium hypochlorite does not remove all the material from the root canal. The walls of a root canal are comprised of dentin, which contains millions of dentinal tubules per square millimeter. Instruments used to negotiate and shape a canal cut dentin and dentin, in combination with organic substrates, forms dentinal mud. Dentine mud, pulp, bacteria, and other related irritants have been consistently visualized histologically after cleaning and shaping procedures in the dentinal tubules and various aspects of the root canal systems. Thus, after cleaning and shaping procedures, the root canal is still covered with a film of debris, frequently described in the literature as a “smear layer.” This “smear layer” includes dentinal mud and/or organic debris, including the irritants noted above.
After cleaning and shaping, the root canal has been traditionally filled with gutta percha and a root sealer. However, if the smear layer or film is not adequately removed from the root canal, the smear layer can compromise the filling and sealing of the root canal system. If obturation is incomplete then the root canal space is predisposed to bacterial leakage and failure. Post-treatment failures attributable to leakage are common and require endodontic retreatment of the tooth or extraction. Thus, for a complete and thorough cleaning, this smear layer or film should be removed. To address the smear layer, practitioners use a weak acid or surfactant, such as 17% EDTA, in an effort to remove the smear layer. Typically, the root canal is flushed with EDTA, or other similar reagents, to accomplish this. Traditionally, some practitioners have used a metal root canal file or a cannula to activate the solution and enhance the performance of the EDTA. These devices may be used manually or mounted in an ultrasonic handpiece to produce vibrations and fluid movement. As an example, even when a file is used, it is impossible to ensure that the file is brought into contact with the complete surface of the root canal, and hence it is difficult to ensure that substantially all of the smear layer has been removed. Regrettably, the use of ultrasonically driven metal instruments has frequently led to iatrogenic events, such as broken instruments, ledges in the wall of the root canal preparation, or even perforation of the root canal.
In my prior patent, U.S. Pat. No. 6,179,617, which is incorporated herein by reference, I disclosed an endodontic brush for use in removing the smear layer. The brush is comprised of a handle, a shank and a brush section extending from the shank. The brush section includes a plurality of bristles extending from a twisted wire core. While this brush works acceptably, it still has many shortcomings which are due to the fact that the core and shank are disclosed to be made from wire. The two twisted wires which form the core and shank are each 0.2 mm in diameter, and hence, the core and shank have a diameter of at least 0.4 mm. While the wires are quite thin, even without bristles, the device, at times, has a diameter that is too large to reach the end of many canals. From a technical standpoint, the wires cannot be made much thinner because the brush would then become predisposed to breakage during use. Even at the current diameter, the wire shank and core are too flexible. Because of its high flexibility, an endodontist cannot effectively and purposely brush the sides of the root canal wall, using a brushing manner, and hence cannot thoroughly remove the smear layer from the root canal preparation. Additionally, because of the twisted wire core, the brush cannot be driven ultrasonically. The twisted wire core prevents the optimal transfer of ultrasonic energy to the bristles of the brush.
Since the brush is too large for well-prepared, yet smaller diameter canals, I have found that when the brush is placed into the canal, the irrigant in the canal is partially displaced by the brush. This is undesirable as it is the irrigant that dissolves the smear layer. Whether the brush, disclosed in my above noted patent, or a file, is used to clean a prepared canal, the addition of fresh irrigant requires that either tool be removed from the canal to allow for fresh irrigant to be introduced into the canal.
Additionally, prior sonic or ultrasonically driven endodontic tools require that the tool be attached to a driver by means of wrenches. This makes it difficult (and sometimes time consuming) to change tools during a procedure. It would be desirable to make it easier to attach the tools to, and remove then from, their drivers.